Network applications such as virtual private network (VPN), voice over IP (VoIP) or voice over frame relay (VOFR) network may require an IP service provider (ISP) to monitor data packet loss in a network and/or inter-packet jitter (inter-packet latency in arrival time). Such network applications may be required as a part of a service level agreement (SLA) between an ISP and a user/client. The service provider needs a way to measure data packet jitter, latency and loss and the users/clients need a way to monitor data packet jitter and loss to ensure they are getting the level of service the ISP agreed to provide.
The use of real-time applications has made it essential that the performance monitoring applications which actively or passively probe the network should do so in a manner which is reliable and in a manner that attempts to overlap with the underlying network characteristics, thereby to observe network performance degradations as they happen.
Although the simplest way to collect performance parameters from the network is by conducting periodic sampling of the network, at regular intervals, this type of scheduling of probes may be insufficient. The main reason for this is that the underlying network may also exhibit a periodic nature, e.g. periodic routing updates, which may make it highly probable that only a non-representative part of the network characteristic will be captured or observed.
Prior art systems schedule operations or probes at fixed intervals, and may further vary the inter-packet delay, for example the delay between packets forming one monitoring probe. These methods have proved to be insufficient and too cumbersome to efficiently monitor network characteristics. It has further been found that prior art systems may be unreliable for jitter measurements.